Why Bengali kasundi is the most powerful mustard sauce you've never tried

Indian Express

3 days ago

Imagine a slice of soft white bread, layered with sharp Colman's mustard, and topped with either boiled, shredded chicken or mashed eggs. It's the mustard that gives it the edge—the sharpness and vinegary tinge elevating the simplest of sandwiches or dishes to another level. I'm a big fan of mustard—not the shorshe or sarson used in Bengali curries, but the kind made into a sauce, served as an accompaniment to various dishes. And one of my absolute favourites is Bengal's kasundi.
The making of Bengali kasundi is nothing short of a rite. I come from a home where it never played a starring role on the dining table. Despite enjoying some of the finest Bengali cuisine, kasundi wasn't something we ate or served much—and so it was never made at home either. Like sandesh and many Bengali sweets, which are tedious to prepare, kasundi is widely available across Bengal, bottled and sold by numerous small and large manufacturers.
So why this sudden ode to kasundi? Because of a food guide that's been stirring up debate in culinary circles in recent years. TasteAtlas—a relatively new guide from Croatia that launched in 2018—ranks everything from global dishes and restaurants to ingredients. Naturally, these rankings cause much heartburn, particularly when they seem misinformed or arbitrary.
Their latest list, on the world's best mustards, included several German, French, English and even Chinese varieties. But not that most nuanced of mustards—Bengali, and therefore Indian, kasundi, which is sharp enough to clear your sinuses.
Mustard—sarson, sometimes rai—is widely used across India, either for tempering or as a paste to flavour dishes. The leaves are cooked into sarson ka saag, or sautéed like spinach in many regions. But only in Bengal is mustard turned into a sauce that could rival the finest mustards in the world. We eat it with spinach, drizzled on top, or as a dip for crumb-fried fish or 'chops.' It's sharp, piquant, and utterly delicious.
Making kasundi, however, isn't as simple as blending mustard seeds with water and salt. And neither is its past.
I suspect the reason kasundi was never made at home is because we didn't observe certain archaic or regressive customs—especially those rooted in caste or gender roles. Traditionally, kasundi was only to be prepared by Brahmins. I can't imagine my very educated and independent great-grandmother following such a rule. Hence, we stuck to bottled kasundi.
Kasundi is traditionally made on Akshaya Tritiya, in the Bengali month of Baishakh, right after the mustard harvest. According to old customs, only Brahmin men were allowed to make kasundi. Even Brahmin women could only wash, dry, and pound the mustard seeds—not make the actual paste. I've never seen this rule followed, even in the most traditional Bengali homes—but it is what the old prescriptions say.
What I have witnessed is kasundi being made in a kitchen—and the sheer complexity of the process amazed me. This is a sauce that's been prepared for centuries, without any fancy tools, using bare hands and traditional knowledge. Over a dozen spices—green and black cardamom, cumin, coriander, nutmeg, mace, long pepper, chillies, black pepper, and the uniquely Bengali radhuni (wild celery seeds)—are used to create the spice mix that gives kasundi its signature punch.
What sets one kasundi apart from another is the exact mix and measure of these spices. Once dried, the mustard seeds and spices are pounded and sifted, then mixed with water, salt, and vinegar. Before refrigeration, this mixture would be stored in earthen pots and sealed for two and a half days in a cool, dark place. A version called phool or aam kasundi is made with turmeric, chillies and green mango, for an added flavour kick.
The closest mustard I've found to kasundi is Colman's. Especially the powdered version, when mixed with water, it comes close in sharpness and tang. But here's the thing: you never cook with kasundi, contrary to what many modern recipes suggest. It's a dipping or flavouring sauce, meant to be eaten as is. It's also one of those rare Indian condiments that has no regional variant outside Bengal.
My advice: Eat it the way it's meant to be eaten. Be a purist. Don't slather it on your sandwich; for that, there's Dijon. Instead, have it with fish fry or drizzled over sautéed spinach with steaming hot rice. That's when you'll realise how the simplest ingredients can deliver the most complex tastes.
Below is the only kasundi recipe I've ever followed. I made it once, and it's absolutely worth trying.
1 bay leaf
1 tsp black peppercorns
¼ tsp ajwain (carom seeds)
¼ tsp radhuni/celery seeds
1 tsp cumin seeds
1 tsp coriander seeds
½ tsp fenugreek seeds
2 cloves
2 tbsp white vinegar
2 tbsp mustard oil
½ tsp turmeric powder
1 cup yellow mustard seeds
½ cup black mustard seeds
2 dried red chilis
2 green cardamoms
1 tsp salt
1. In a bowl, mix all the dry ingredients, except turmeric and salt.
2. Heat a pan and dry roast the spices over low heat till they are fragrant and start to crackle.
3. Do not let the mixture burn; allow it to cool and then grind to a fine powder.
4. Start adding boiled and then cooled water to this powder slowly, to create the consistency of mustard paste. Now add the turmeric. The consistency should be thick.
5. Stir in the salt and white vinegar.
6. Transfer the mixture to a glass jar, add the mustard oil over the paste. Do not stir into the paste – this is simply to ensure that the top layer of the paste is covered. Keep the closed jar in the fridge for at least a week or 10 days, allowing it to ferment before you dig in.
Next week, I'll be writing about Lady Canning. Why? You'll have to read to find out.